<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        do {
            var yerr = prompt("请输入你的出生年分:");
        } while (yerr == "")
        if ((yerr % 4 == 0 && yerr % 100 != 0) || (yerr % 400 == 0)) {
            alert("你出生的年份" + yerr + "是闰年");
        } else {
            alert("你出生的年份" + yerr + "不是闰年");
        }
    </script>
</head>
<body>

</body>
</html>